According to a straight reading of evolutionary theory, an animal should plump for the physically fittest mate so that their offspring inherit the best possible mix of genes. But sexual attraction is a complicated affair.

A conference at London Zoo last year, called "Why do animals mate with the 'wrong' partner?", examined the various factors that can draw two animals together – and some ill-fated pairings. Here is a selection of the sexual adventures explored at the meeting. David Robson

Humans are not the only animals to consider their partner's compatibility with their own personality: bold females of many species tend to go for plucky males, while more shy females will go for more retiring individuals. That might explain why different personality types persist.

Even so, female zebra finches can be swayed by a male's popularity, preferring to choose males that have already struck it lucky with another female. That means they may end up choosing an inferior mate simply because they have seen him enjoying another's attentions.